1. Field of the Invention
The present invention relates to the correction of a printing error in an inkjet printer, and more particularly, to a method and apparatus to correct printing errors relating to improper paper movement caused by a feed roller.
2. Description of the Related Art
In general, inkjet printers print various materials that are displayed on computer monitors on print paper according to electric signals received from a computer. Generally, inkjet printers have a pickup roller, a feed roller, one or more printer heads, and an exhaust roller. During the printing process of an inkjet printer, print paper contained in a paper cassette is supplied by a pickup roller to the feed roller one sheet at a time. The print paper supplied to the feed roller is supplied to the printer head by the constant-speed driving of the feed roller. The printer head then prints on the supplied print paper. After printing, the paper is output from the inkjet printer by the exhaust roller.
However, when a trailing end of a sheet of print paper passes the feed roller while being moved toward the printer head, print quality can be lowered due to the excessive movement of the paper. In other words, when the feed roller rotates by a predetermined distance a, the print paper is exhausted by the distance a as well. When the trailing end of the print paper passes the feed roller, the print paper exhausted by the distance a is further exhausted by a distance “a+α=L” by the feed roller and the exhaust roller so as to be excessively exhausted by a distance α. Thus, a blank area the length of α can be generated on the print paper. Since there is a drag force present that corresponds to the force of the feed roller pulling the print paper, and the pulling force disappears when the print paper escapes from the feed roller, the print paper is overly exhausted by the distance α. Also, the height of the trailing end of the print paper changes when the trailing end of the print paper passes the feed roller. The printer head ejects ink onto a portion of the paper where the ink is already ejected so that an undesirable print state is generated. Thus, when the trailing end of the print paper passes the feed roller, the above problems can occur.